/Engine/Source/Runtime/HeadMountedDisplay/Public/IXRTrackingSystem.h
Called just after the late update on the render thread passing back the current relative transform.
virtual void OnLateUpdateApplied_RenderThread ( [FRHICommandListImmediate](API\Runtime\RHI\FRHICommandListImmediate) & RHICmdList, const FTransform & NewRelativeTransform )